scholarly journals Thermal Stability Changes in Telomeric G-Quadruplex Structures Due to N6-Methyladenine Modification

Epigenomes ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 5 ◽  
Author(s):  
Ryohei Wada ◽  
Wataru Yoshida
Keyword(s):  
Thermal Stability ◽  
Base Pair ◽  
Genomic Dna ◽  
Biological Functions ◽  
Duplex Structure ◽  
Stacking Interaction ◽  
Hybrid Type ◽  
G Quadruplex ◽  
Melting Analysis ◽  
Thermal Stability Of

N6-methyladenine modification (m6dA) has recently been identified in eukaryote genomic DNA. The methylation destabilizes the duplex structure when the adenine forms a Watson–Crick base pair, whereas the methylation on a terminal unpaired adenine stabilizes the duplex structure by increasing the stacking interaction. In this study, the effects of m6dA modification on the thermal stability of four distinct telomeric G-quadruplex (G4) structures were investigated. The m6dA-modified telomeric oligonucleotide d[AGGG(TTAGGG)3] that forms a basket-type G4 in Na+, d[(TTAGGG)4TT] that forms a hybrid-type G4 in K+ (Form-2), d[AAAGGG(TTAGGG)3AA] that forms a hybrid-type G4 in K+ (Form-1), and d[GGG(TTAGGG)3T] that forms a basket-type G4 with two G-tetrads in K+ (Form-3) were analyzed. Circular dichroism melting analysis demonstrated that (1) A7- and A19-methylation destabilized the basket-type G4 structure that formed in Na+, whereas A13-methylation stabilized the structure; (2) A15-methylation stabilized the Form-2 G4 structure; (3) A15- and A21-methylations stabilized the Form-1 G4 structure; and (4) A12-methylation stabilized the Form-3 G4 structure. These results suggest that m6dA modifications may affect the thermal stability of human telomeric G4 structures in regulating the biological functions.

Spectral properties and thermal stability of AS1411 G-quadruplex

2015 ◽  
Vol 72 ◽  
pp. 806-811 ◽  
Author(s):  
Zeinab Bagheri ◽  
Bijan Ranjbar ◽  
Hamid Latifi ◽  
Mohammad Ismail Zibaii ◽  
Tahereh Tohidi Moghadam ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Spectral Properties ◽  
G Quadruplex ◽  
Thermal Stability Of

scholarly journals Second generation silver(I)-mediated imidazole base pairs

2014 ◽  
Vol 10 ◽  
pp. 2139-2144 ◽  
Author(s):  
Susanne Hensel ◽  
Nicole Megger ◽  
Kristina Schweizer ◽  
Jens Müller
Keyword(s):  
Thermal Stability ◽  
Melting Temperature ◽  
Base Pair ◽  
Metal Ion ◽  
Second Generation ◽  
Dna Duplex ◽  
Base Pairs ◽  
Double Helices ◽  
Thermal Stability Of

The imidazole–Ag(I)–imidazole base pair is one of the best-investigated artificial metal-mediated base pairs. We show here that its stability can be further improved by formally replacing the imidazole moiety by a 2-methylimidazole or 4-methylimidazole moiety. A comparison of the thermal stability of several double helices shows that the addition of one equivalent of Ag(I) leads to a 50% larger increase in the melting temperature when a DNA duplex with methylated imidazole nucleosides is applied. This significant effect can likely be attributed to a better steric shielding of the metal ion within the metal-mediated base pair.

scholarly journals Quantifying the impact of small molecule ligands on G-quadruplex stability against Bloom helicase

2019 ◽  
Vol 47 (20) ◽  
pp. 10744-10753 ◽  
Author(s):  
Parastoo Maleki ◽  
Golam Mustafa ◽  
Prabesh Gyawali ◽  
Jagat B Budhathoki ◽  
Yue Ma ◽  
...  
Keyword(s):  
Gene Expression ◽  
Thermal Stability ◽  
Small Molecule ◽  
Single Molecule ◽  
Telomerase Activity ◽  
G Quadruplex ◽  
Small Molecule Ligands ◽  
The Impact ◽  
Different Levels ◽  
Thermal Stability Of

Abstract G-quadruplex (GQ) stabilizing small molecule (SM) ligands have been used to stabilize human telomeric GQ (hGQ) to inhibit telomerase activity, or non-telomeric GQs to manipulate gene expression at transcription or translation level. GQs are known to inhibit DNA replication unless destabilized by helicases, such as Bloom helicase (BLM). Even though the impact of SM ligands on thermal stability of GQs is commonly used to characterize their efficacy, how these ligands influence helicase-mediated GQ unfolding is not well understood. Three prominent SM ligands (an oxazole telomestatin derivative, pyridostatin, and PhenDC3), which thermally stabilize hGQ at different levels, were utilized in this study. How these ligands influence BLM-mediated hGQ unfolding was investigated using two independent single-molecule approaches. While the frequency of dynamic hGQ unfolding events was used as the metric in the first approach, the second approach was based on quantifying the cumulative unfolding activity as a function of time. All three SM ligands inhibited BLM activity at similar levels, 2–3 fold, in both approaches. Our observations suggest that the impact of SM ligands on GQ thermal stability is not an ideal predictor for their inhibition of helicase-mediated unfolding, which is physiologically more relevant.

The Ordered Phase Formation in Ti-Al-Ga Alloys

1970 ◽  
Vol 28 ◽  
pp. 440-441
Author(s):  
Shiro Fujishiro ◽  
Harold L. Gegel
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Titanium Alloys ◽  
Growth Kinetics ◽  
Stoichiometric Composition ◽  
Good Potential ◽  
Alpha Titanium ◽  
Cold Rolled ◽  
Kinetics Of ◽  
Thermal Stability Of

Ordered-alpha titanium alloys having a DO19 type structure have good potential for high temperature (600°C) applications, due to the thermal stability of the ordered phase and the inherent resistance to recrystallization of these alloys. Five different Ti-Al-Ga alloys consisting of equal atomic percents of aluminum and gallium solute additions up to the stoichiometric composition, Ti3(Al, Ga), were used to study the growth kinetics of the ordered phase and the nature of its interface.The alloys were homogenized in the beta region in a vacuum of about 5×10-7 torr, furnace cooled; reheated in air to 50°C below the alpha transus for hot working. The alloys were subsequently acid cleaned, annealed in vacuo, and cold rolled to about. 050 inch prior to additional homogenization

Microstructure studies of tungsten silicide schottky contacts on Gaas

1987 ◽  
Vol 45 ◽  
pp. 328-329
Author(s):  
Yih-Cheng Shih ◽  
E. L. Wilkie
Keyword(s):  
Thermal Stability ◽  
Field Effect Transistors ◽  
Schottky Contact ◽  
Schottky Contacts ◽  
Excellent Thermal Stability ◽  
Barrier Heights ◽  
Gaas Substrates ◽  
Film Adhesion ◽  
Threshold Voltages ◽  
Thermal Stability Of

Tungsten silicides (WSix) have been successfully used as the gate materials in self-aligned GaAs metal-semiconductor-field- effect transistors (MESFET). Thermal stability of the WSix/GaAs Schottky contact is of major concern since the n+ implanted source/drain regions must be annealed at high temperatures (∼ 800°C). WSi0.6 was considered the best composition to achieve good device performance due to its low stress and excellent thermal stability of the WSix/GaAs interface. The film adhesion and the uniformity in barrier heights and ideality factors of the WSi0.6 films have been improved by depositing a thin layer of pure W as the first layer on GaAs prior to WSi0.6 deposition. Recently WSi0.1 has been used successfully as the gate material in 1x10 μm GaAs FET's on the GaAs substrates which were sputter-cleaned prior to deposition. These GaAs FET's exhibited uniform threshold voltages across a 51 mm wafer with good film adhesion after annealing at 800°C for 10 min.

Thermal stability of Al-Cu-Fe icosahedral alloys

1991 ◽  
Vol 1 (12) ◽  
pp. 1823-1836 ◽  
Author(s):  
M. Bessière ◽  
A. Quivy ◽  
S. Lefebvre ◽  
J. Devaud-Rzepski ◽  
Y. Calvayrac
Keyword(s):  
Thermal Stability ◽  
Thermal Stability Of
Sign in / Sign up

Export Citation Format

Share Document